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By T. Wisdom, D. Romo, G. Seale, R. Jansen

Thickening remains relatively misunderstood since it is typically near the end of the process and not directly involved in metal recovery. When operating well, thickeners are ignored and left to run independently, the ‘out of sight, out of mind’ phenomena. However, when operating poorly, there is a lack of basic understanding and remedial actions to solve issues are reactionary rather than proactively addressing shortcomings. This series of papers breaks down in sequential order the stepped phases required to gain an appreciation and thorough understanding of the science behind thickeners, and key thickener components, and basic troubleshooting skills. This second paper starts with identifying the different approaches to thickener test work including static and dynamic settling tests followed by high-rate versus paste thickening. Complimentary to test work, the mechanisms surrounding coagulation and flocculation are presented and explained. The basic mechanisms for coagulation and flocculation are discussed to support the different test work approaches and provide the reader with the basic background.

Mar 2, 2022

By Michelle Pienaar, Musa S. D. Manzi, Thabang Kgarume, Glen T. Nwaila, Raymond J. Durrheim, Abrie Oberholster, Hennie Grobler

The South African Mining, Extraction, Research, Development and Innovation (SAMERDI) strategy was launched in 2019 with the goal of modernizing the mining industry. It comprises three major research initiatives: improvement in the efficiency of extraction and health and safety in current mining operations, development of fully mechanized systems to mine narrow tabular ore bodies in hard rock, and development of extraction systems to break rock without using explosives. The crosscutting Advanced Orebody Knowledge (AOK) program seeks to develop and implement drilling and geophysical technologies that can characterize the rock mass ahead of mining and identify potentially hazardous geological features. This knowledge will be integrated with information derived from seismic monitoring. Mining methods, layouts and rock support systems will be adjusted accordingly to mitigate the risk of rockbursts. Boreholes are routinely drilled ahead of mine workings using diamond-impregnated bits. The drill core is logged to identify lithology and geological structures (especially dykes and faults that may be seismogenic), sample the ore body for grade control, and detect areas that may contain water and/or flammable gas. Methods and technology to improve the efficiency of drilling and maximize the information obtained from the drilling process, borehole core, and the borehole itself are being investigated. A range of geophysical technologies are being developed to map the rock mass from the skin of the excavation to a distance of several tens of meters. Light Detection and Ranging (LiDAR) is used to map the geometry of the excavation, including prominent joint, vein and fracture sets and the presence and performance of rock support elements and systems. Ground Penetrating Radar (GPR) is used to penetrate deeper into the rock mass and image joints, fractures bedding planes that influence the stability of the hanging and side walls. Image processing techniques known as ‘seismic attributes’ are being applied to the radargrams to improve interpretation. Electrical Resistivity Tomography (ERT) and various active and passive seismic techniques (e.g. Tunnel Seismic Profiling (TSP), ambient noise tomography) achieve even greater penetration into the rock mass. Finally, machine learning is used to improve the processing and interpretation of seismic and radar data.

Apr 26, 2022

By Hemendra N. Kalia

To plan a safe and efficient coal mining operation, the design engineer should use all the available information regarding the property to be exploited. The reliability of the mining operation must be as high as possible so that the plants relying on the coal can operate at the maximum design capacity. A good design should incorporate all of the known geological characteristics of the deposit, the structural and physical properties of the coal, as well as the rock which will form the roof and floor of the mine openings. A systematic method is proposed as a guide to insure a mine design that will be safe, efficient and will minimize surface disturbances resulting from mining operations. It is anticipated that the method proposed will result in maximum extraction at perhaps minimum cost to the operator. In general, to develop a mining area, several factors are systematically reviewed: (1) determination of the economic minability of the deposit, (2) the computation of the coal reserves, (3) the marketability of the coal, and (4) the life of the property. In general, boreholes are drilled in a predetermined pattern and geophysical or geological methods are used to log the boreholes. The information so obtained is primarily used to determine the quality and the extent of the deposit and to determine to some extent such geological features as faults, barren areas, washouts, and channels.

Jan 1, 1973

By T. A. P. Sankar, S. Gundiah, Pradip, R. A. Kulkarni

Two modified polyacrylamide flocculants, namely polyacrylamide with glycolic acid functionality (PAMG), and a copolymer of acrylamide with N-acryloyl-[T]- aminobutyric acid (HPVP), were synthesized, characterised and evaluated for selective separation in apatite/quartz and apatite/dolomite/calcite systems, respectively. PAMG flocculant was found selective in the separation of tricalcium phosphate (TCP) from its mixtures with quartz at acidic to neutral pH range. The selectivity deteriorated at alkaline pH. In contrast, polyacrylic acid (PAA) flocculant was found most effective only in the alkaline pH range. HPVP flocculant (even though flocculating all three minerals namely apatite, dolomite and calcite) was observed to be quite selective for the separation of calcite from apatite-dolomite minerals in single mineral tests in the presence of sodium hexametaphosphate dispersant at neutral pH. There was, however, no selectivity observed during tests on synthetic mixtures. This loss in selectivity is attributed to the phenomenon of hetero-flocculation, as reported earlier, for separation in an apatite-dolomite system with polyethylene oxide.

Jan 1, 1993

By Karl P. Norrena, Clayton V. Deutsch

Ore and waste cannot always be visually separated. The distinction between ore and waste may need to be made on the basis of blasthole sampling. Hand drawn dig limits or computer-generated contour lines do not account for uncertainty, economics or equipment. Geometric methods for interpreting grade information such as the polygonal or triangulation methods share the same limitations as contouring. Geostatistical techniques exist for the realistic modeling of grade variations and uncertainty. Decision analysis techniques exist for the binary classification of ore, and waste blocks in the presence of this uncertainty. Block-by-block classification is not enough; mining equipment cannot exercise free selection of blocks. There is a need for procedures to determine optimal dig limits that account for (1) the uncertainty in the grades, (2) the economics of risk-qualified decision-making, and (3) the ability of the mining equipment to dig to specific limits. This paper presents a procedure for optimal determination of dig limits that account for these constraints. Simulated annealing (SA) is used with modest computational requirements because the number of variables is relatively small. The solution of the optimization problem is dig limits that maximize profit under multiple constraints. The method is illustrated with different constraints and tested against hand drawn dig limits in a "Dig Limit Challenge," which illustrates the efficacy of the new method.

Jan 1, 2002

By A. L. Ling, A. K. Janzen

"Design of effective mine water treatment plants depends on the ability to reliably predict treatment outcomes, but systems with multiple chemical and physical treatment processes and recycle loops can be difficult to model. GoldPHREEQC is a modeling framework that integrates mass and flow routing capabilities of GoldSim software and water quality calculations provided by PHREEQC, and is well-suited to modeling parameters of interest in the mining industry, especially metals and sulfate. Physical processes such as membrane separation and greensand filtration are modeled by defining mass rejections for each parameter and flow routing based on vendor projections and bench- or pilot-scale equipment testing. GoldPHREEQC models chemical precipitation processes such as HDS metals removal and gypsum precipitation by (1) performing surface-aging and solubility calculations in PHREEQC and (2) using the GoldSim framework to direct supernatant and precipitate to subsequent process steps. Users can apply this modeling framework to predict effluent water quality, chemical requirements, sludge production, and required equipment capacity to support design, troubleshooting, and cost estimating. INTRODUCTION Design of effective mine water treatment plants depends on the ability to reliably predict treatment outcomes, but systems with multiple chemical and physical treatment processes and recycle loops can be difficult to model. GoldPHREEQC is a modeling framework that integrates mass and flow routing capabilities of GoldSim software (1) and water quality calculations provided by PHREEQC (2), and is well-suited to modeling treatment of parameters of interest in the mining industry, especially metals and sulfate. GoldPHREEQC can also be applied to other water treatment scenarios using inorganic reactions and processes. The GoldPHREEQC model framework moves water and mass between specified model nodes and calculates specified reaction and water quality outcomes. It can be organized to provide flow, load, and concentration information for each location, including effluent and byproduct streams, and outputs can be adapted to include power and chemical costs."

Jan 1, 2018

By Vasiliki Founta, Andrew J. Whittle

"This paper describes the development of a 3D finite element model for predicting ground movements caused by construction of 7.1 m diameter twin bored tunnels for the Crossrail project in London using Earth Pressure Balance (EPB) machines. The model uses the commercial FE code, Plaxis 3D, to represent the face pressure, conical shield, grouting process and activation of precast segmental concrete lining systems through a set of boundary conditions that advance through the soil mass along a prescribed trajectory. Soil behavior is described using the Mohr-Coulomb soil model with input parameters calibrated from laboratory element tests. The analyses focus on the performance of the EPB tunneling machines in greenfield conditions beneath Hyde Park, where the tunneling occurs within deep layers of relatively uniform London Clay. The model predictions are in good agreement with surface and sub-surface vertical settlements measured at a well-instrumented section, but tend to overestimate the measured lateral displacements towards the tunnel. Ongoing studies are focused on the role of soil behavior and the approximations in FE model predictions of tunnel-induced ground deformations. Introduction Since their introduction in the 1970’s, closed-face Earth Pressure Balance (EPB) machines have become widely used for soft ground tunnel construction. The EPB design relies on a screw conveyor system to regulate the pressure of the excavated soil/spoil within the head chamber and hence control stability at the face of the machine. One of the key design issues in the application of EPB machines is to establish how control parameters, including the advance rate, face pressure and grouting processes (used to compensate for the tail void at the rear of the shield and to infill gaps between the precast lining rings and surrounding soil) affect and/or control the far-field ground movements. For closed-face systems, short-term deformations are associated with ground losses at the face, overcutting and ploughing of the shield and poor control of grouting in the tail void; while long-term deformations can occur due to consolidation and creep within the surrounding soil (and are closely connected to the seepage boundary conditions;e.g., Laver & Soga, 2012). The control parameters for advancing the EPB machine can have a significant effect on the magnitude and distribution of the far-field deformations. Therefore, analyses of the ground response to tunneling require accurate modeling of the soil stratigraphy and constitutive behavior as well as the construction process. Finite element (FE) methods have been used to simulate tunnel construction since the early 1980s, but only a few studies involved three-dimensional modelling of mechanized tunneling (e.g., Finno and Clough 1985; Bernat and Cambou 1999; Swoboda and Abu-Krisha 1999; Dias et.al. 2000; Melis et.al. 2002; Kasper and Meschke 2004; Möller 2006). In order to get a better understanding of the effect of the construction process and soil properties on the development of the ground deformations more comprehensive models of tunnel excavation and tunnel support are required in order to capture the 3D nature of mechanized tunneling and the effect of construction parameters such as advance rate, face and grout pressure."

Jan 1, 2016

By D. V. Bush

The economic application of real time computer control can be broken down into 2 broad areas of concern. The first would be in gaining the most efficient utilization of energy. The second would be in improved product quality. This paper will be primarly concerned with the first area of efficient energy utilization as that area has the greatest effect on costs and thus net profits. Most process control strategy attempt to achieve the greatest comminution with the least amount of energy thus maximizing efficiency. A more direct approach to energy control involves a total mine and mill energy management system. In most cases these systems have an ability to achieve a very short payback period with the greatest return on investment.

Jan 1, 1986

By Raj K. Rajamani

In ball milling the rates of breakage vary primarily with the size distribution of powder in the mill. In wet grinding viscosity of the slurry varies continually as size distribution changes and hence the breakage rates change. In this study a simpler estimation scheme is used to determine breakage rates in batch grinding. Using an approximate solution to the batch grinding equation, acceleration and deceleration of breakage rates of all individual size classes is determined when the grinding environment is varied. Experimental results with limestone and copper ore show time-dependent breakage rates under both dry and wet grinding conditions. In general the breakage rates increase for coarse sizes and decrease for fine sizes with increase in the fines present in the mill. Such variations have strong implications in closed-circuit grinding.

Jan 1, 1991

By D. Eyde

The zeolites review arrived too late for the June issue. The natural zeolite industry continues to grow even as some companies look for the exits. Production for 1993 was estimated at between 42 and 44 kt (46,000 and 48,000 st). That is between 7 and 9 kt (7700 and 9900 st) above 1992 production. GSA Resources, Saint Cloud Mining, Steelhead Specialty Minerals, Teague Minerals, UOP and Zeotech all reported continued growth last year. At the same time the East-West Minerals' Eastgate mordenite mine, and American Resources' Ash Meadows clinoptilolite operations both shut down their processing plants and are attempting to sell the mines and facilities. In addition, Tenneco Minerals continued its attempt to sell the Mud Hills clinoptilolite deposit. Unimin entered the natural zeolite industry through its acquisition of several properties of Aimcor. The properties included the Ben-Jel bentonite and Castle Creek clinoptilolite deposits and processing facilities near Caldwell, ID

Jan 1, 1994

By T. M. Hanna

The results of using a simple analytical solution and a relatively complex numerical model to estimate ground-water inflow to an open pit mine are compared. The analytical solution assumes lateral, radial flow to a fully penetrating pit in an idealized confined aquifer, whereas the numerical model simulates fully three-dimensional flow to a partially penetrating pit from a water table aquifer. The latter is obviously a more realistic simulation of the problem, but the former method is significantly easier to use, Comparison of the results obtained with the two methods for some typical hydrogeologic conditions encountered in mining yields ratios between them in the range of 0.15 to 0.60. These values can be used as a coefficient in the Pit Flow analytical solution to produce reasonable estimates of in-flow even when there are significant differences from the idealized conditions implicit in its application.

Jan 1, 1992

By Michael Drozd

The operation of an activated charcoal system has five separate unit operations. These unit operations have common points for CIP, CIL and CIS system, which vary widely in application. a. Absorption b. Desorption (Stripping) c. Acid Washing d. Reactivation e. Carbon Handling ( carbon transportation, sizing, de­watering, etc.) Cost optimization starts with the basic operating parameters (design philosophy) set down at the time of engineering design. This parameters undergo almost immediate change due to site specific ore requirements, throughput changes, operator requirements or reagent availability. Activated charcoal is sometimes viewed as simple, uncomplicated reagent that requires not optimization. To some extent, this statement is true, but under most circumstances, if the time necessary to optimize the use of activated charcoal is available, the effort is rewarded with significant savings. CPL-Carbon Link has embarked upon a program of supplying technical support with its activated charcoal. Several operation in the United States have under taken to have CPL-Carbon Link do an operational survey to determine if potential savings are possible. CPL-Carbon Link has offered to do these surveys for projects that are clients or simply would like to have CPL-Carbon Link review their operation. The information accumulated by CPL-Carbon Link is being used to attempt to fashion industry standards so that a common reference point came be establish for activated charcoal usage.

Jan 1, 2000

By Terry M. Hertel

The chemistry of waters processed by Acid Rock Drainage water treatment plants can affect the Total Suspended Solids quality of the plant effluents. The sulfate ions in the ARD water will combine with the calcium ions from the lime that is used to adjust pH to form calcium sulfate. When the sulfate content of the waters to be treated is greater than about 1400 parts per mil­lion, the resulting calcium sulfate concentration will be approx­imately 2100 parts per million. This concentration is above the saturation point for calcium sulfate, and the salt will drop out of solution until the concentration falls below the saturation point. This "salting" phenomenon affects the total suspended solids of the treatment plant effluents by virtue of the fact that the salts will report to the filtration apparatus used for the analy­sis. This scenario is exacerbated as an effluent sample ages. Zortman Mining's water treatment plant effluent was being affected by "salting" during the spring and summer of 1995, and it seemed as though the effluents were exceeding the TSS lim­its; for no obvious reason. A testing program was initiated to verify an observation that "salting' was taking place. Treatment plant samples were collected and allowed to age, with TSS analyses being performed every day that the samples aged. Synthetic solutions were also prepared to study the "salting" phenomenon.

Jan 1, 1996

By James A. Commins

Accurate engineering predictions of energy needs for pollution control equipment used in surface mining operations is critically important to sound management selection of control alternatives. This paper will describe a procedure for evaluating two control alternatives with different energy needs. Three steps are involved: an analysis of the pertinent regulations, a determination of the size distribution of the particles being emitted, a calculation of the energy needs and costs of the candidate control systems as a function of these regulations and emission characteristics. The principal air pollutant to be controlled in surface mining operations is particulates, or dust, some of which is already on the material introduced into the primary crusher and other dust which is generated by the various steps in the subsequent processes. The requirement for control stems both from regulations concerning workers at the operating site, and the community surrounding the operations. In order to speak quantitatively about the need for control we will use regulations that pertain in Pennsylvania although it must be borne in mind that such regulations vary according to juristiction.

Jan 1, 1975

By Michael Gay

Right in the heart of Boston Harbor lies Deer Island, where a ten-year, 6 billion dollar sewage treatment plant is under construction. The 9.5 mile long, 25.5' diameter Effluent Outfall Tunnel is the center piece of this program. A Robbins double-shielded TBM is currently driving this challenging tunnel some 400 feet below sea level. This paper will discuss the set-up and operation of this Tunnel Boring Machine in driving the longest single heading tunnel ever built in North America.

Jan 1, 1993

By Nikhil Dhawan, SHAILA MIR

Consumer preference for ever-higher laptop performance coupled with laptops’ declining lifespans make them a significant contributor to electronic waste. An in-depth evaluation of elemental composition and distribution is important for determining metal recovery potential and sustainable recovery processes. In this work, the characterization of individual components of laptops is studied for the systematic identification of important elements and for streamlined and structured recycling, to reduce processing steps and improve economics. A process flowsheet highlighting various recycling routes by targeting metals and various components is also proposed.

By J. R. Kadambi, C. Shingote, J. Furlan, R. Ke

"Hydrocyclone separators are widely used in various industrial applications in the oil and mining industries to sort, classify and separate solid particles or liquid droplets within liquid suspensions, which are considered to be multi-phase systems. Numerous valuable studies have been conducted in recent years to investigate the flow fields inside hydrocyclones. However, much of the information regarding the performance of cyclones in the literature has limitations, based in some part on the respective current-available theoretical models, and much of it cannot be considered as completely applicable to most real-world applications; many of the studies investigated the flow fields within extremely simplified hydraulic designs that are not representative of the complex geometries or large sizes which are typical in industry. Therefore, in this study, the two phase flow system inside the actual hydraulic geometry of a milling circuit hydrocyclone was explored with the aid of both computational and experimental techniques (Particle Image Velocimetry). In this study, the flow field with an air core has been investigated; in essence, the research was a two-phase problem, which caused some challenges on both the computational and experimental sides. Two turbulence models were used in the numerical calculations: the Reynolds Stress Model and Large Eddy Simulation. The computational studies are mainly focused on the prediction of the dimensions and shape of the air core. Different section planes of the hydrocyclone were selected as planes of interest and then were divided into several fields of view (FOV) for PIV measurements. Two dimensional experimental velocity vector maps were obtained in each of the fields of view. The computational results were validated globally using pressure and flow rate readings at the boundaries and locally by comparison to the PIV velocity vector maps and profiles. Keywords: Computational fluid dynamics (CFD); Hydrocyclone; Particle image velocimetry (PIV); Reynolds Stress Model (RSM); Large Eddy Simulation (LES). INTRODUCTION A hydrocyclone is a device used to separate a solid-liquid, liquid-liquid, solid-gas, or liquid-gas suspensions into at least two separate density or particle size components. Hence, the flow field of the hydrocyclone is generally considered a multi-phases flow system. Application of hydrocyclones have been used in numerous industries including oil, drilling, metal working, and mineral processing since 1891, when E. Bretney obtained the first patent for the predecessor design of all contemporary hydrocyclones. A modern hydrocyclone typically consists a cylindrical section at the top where the liquid is being fed tangentially, and a conical chamber attached to the bottom of the cylindrical section, as shown in Figure 1. The characteristics of the feed stream that is injected into the cylindrical chamber play a significant role in hydrocyclone operation. The inlet is tangential relative to the cylindrical chamber and hence causes a centripetal force in the flow field which is considered as the primary separation mechanism."

Jan 1, 2017

By W. J. Cieslewicz

Geologically, northeastern Siberia is a region occupied by a folded belt of Triassic and Jurassic sediments and volcanics. Gold mineralization is of Upper Jurassic age. Most of the stream placers formed during the Quaternary. Placer gold was first discovered in 1916. Between 1930 and 1957, mining was carried out by the "Dal 'stroi," a Russian concentration camp organization. Since 1966, the mines have been worked mechanically. About 10 mining districts are now active, producing, altogether, 110 to 135 t (120 to 150 st) of gold annually.

Jan 1, 1987

By Matthew Horsnell

Greenbank Terotech is a member of the Halley & Mellowes Group of Companies and is accredited t AS3902. Greenbank has been involved within the wear resistant lining industry for over 20 years. Initially supplying cast Basalt piping systems through to the present day breakthroughs with SiTech cyclone linings. The challenge of finding the most cost effective cyclone lining has been a difficult process. Over the years many varieties of ceramics have come and gone. In particular within cyclone applications, many people have become disillusioned with the term "Ceramic." In practice, it was discovered that if a ceramic worked in one part of the plant, it did not necessarily work in the cyclone area. A good example of this is Alumina chute and pipe linings. An Alumina lined cyclone underflow bend would provide exceptional wear resistance, whereas an Alumina Spigot would have failed miserably. After Alumina's were tried, Silicon Carbides were experi­mented with. The results in many trials were mixed. What worked at one mine did not work at another. The results did not conclude decisively that ceramics were here to stay within the hard rock cyclone area. It was then that Greenbank Terotech started to look at the reason "Why do some linings work and others don't." We came to the conclusion that the matrix holding the particles together had to be the key to a successful cyclone material. At the time we looked at materials such as Alumina Bonded Silicon Carbides, Metallic (Aluminium) Bonded Silicon Carbide, 99% Alumina Ceramics and Nitride Bonded Silicon Carbides, but all these materials either suffered from chemical attack on the Aluminium matrix (via cyanide) or the matrix simply was not hard enough causing wear rates to be excessive. It was then we looked at SiTech. SiTech is a unique material in that the primary particles are Silicon Carbide, but the matrix is made up of a Secondary Silicon Carbide formed within the reaction bonding process.

Jan 1, 1995

By Alf Thidemann, Per Marius Nilsen

Tunnelling with hydraulic drills has been a success in Norway. In the fall of 1976 excavation of tunnels for the development of the Aabjoera scheme was started. Two and a half years later a total of 25 kilometers of tunnels are completed. During the most busy period 5 rigs with hydraulic drills were in operation. GENERAL INFORMATION. Aabjoera Hydro Electric Plant is located in the central part of Norway (Fig. 1). The scheme covers a mountaineous area between the Tosen Fiord and the valley of Namdalen. Water from the area of precipitation is transferred through 5 tunnels to the main reservoir. From here the water is conducted via a 10 km long, unlined supply tunnel down to the Kolsvik power station. The power station is situated underground with a short tailrace tunnel out in the fiord. Average head of water is 507 m. The Aabjoera plant is jointly owned by Helgeland Kraftlag A/S, 8650 Mosjøen and Nord-Trøndelag Elektrisitetsverk, 7700 Steinkjer. The Civil Engineering Division of the latter company has acted as Consulting Engineers for the scheme. General contractors for the whole scheme has been Ing. F. Selmer A/S, Box 6035, Etterstad, Oslo 6.

Jan 1, 1979